Causes
We do not know exactly what causes type 1 diabetes. It starts with a genetic predisposition to the condition, but often without any diabetes in the family. All kinds of environmental factors can influence whether type 1 diabetes develops.
Scientists have shown that there is a genetic predisposition, but it accounts for only a small part. The chance of developing type 1 diabetes when a family member has it is as follows:
- Brother or sister with diabetes: 1-8%
- Father or mother with diabetes: 1-4%
- Both parents have diabetes: 20-40%
- Cousin with diabetes: 1-2%
- Identical twin with diabetes: 23-50%
A number of environmental factors have been linked to the development of type 1 diabetes: viral infections, certain types of food early in life (including gluten at a very young age) and too little exposure to sunlight (or too little vitamin D). All factors that scientists suspect contribute to the onset of type 1 diabetes.
Diagnosing type 1 diabetes
If type 1 diabetes is suspected, one or more tests are carried out in hospital, including a blood pressure and weight check and a blood sample to measure sugar and/or fat (lipid) levels. The blood sample is best taken while fasting. A fasting blood sugar level of 126 mg/dl (7.0 mM) or higher indicates diabetes. A value between 100 and 125 mg/dl (5.6 and 6.9 mM) is known as impaired fasting glucose or 'prediabetes'. An HbA1c above 6.5% also indicates diabetes.
